Hi. This is an area that’s close to me; I like to hike, play, and map in the areas served by these roads.

The Forest Service Roads, FSRs, generally qualify as tertiary (highway=tertiary) as they are major “through roads” serving a generally large area with a number of smaller roads, and various backcountry “destinations” (oil wells, trail heads, etc.) The wiki for guidance talks about “settlements”, but in the woods, oil wells and the like are equivalent, as destinations. Anyway, I tag most FSRs as tertiary, other than relatively short ones that can be “unclassified”. Note that unclassified is an actual, real classification, blame OSM’s British heritage for that bit of confusion.

I’m not sure what you mean by “ID” and “Unmaintained track road”. Is this some terminology the iD editor uses? Those aren’t keys and tags used in the database, as best I know. (I use JOSM.) We might have a problem if our tools don’t all use the same language.

Temporary roads to access a cutblock would be highway=unclassified, or =track. A road that goes to a single destination, and is maintained, at least for a while. If maintained, unclassified might be better, then track after it starts going back to nature.

Some people map these as service. I generally use unclassified. If the wiki offers guidance, I haven’t managed to find it.

The third class you mention, “parallel sheep trail” etc., would clearly qualify as highway=track. If you can see two tire tracks/ruts, that’s a good guideline in my mind. Powerline tracks (your fourth example), likewise.

The above is my opinion, based on my best interpretation of the wiki, and a wee bit of what I think is common sense. Alberta (my area) mostly follows the above. There was also a similar discussion a few months ago on this forum; some differences, never really resolved and never thus codified into the wiki, alas.